A method for manufacturing a solar cell for power generation is as follows. After a substrate has been prepared, a back electrode layer is formed on the substrate and patterned by a laser, so that a plurality of back electrodes are formed.
Thereafter, a light absorbing layer, a buffer layer, and a high-resistance buffer layer are sequentially formed on the back electrodes. The light absorbing layer may be formed through various schemes such as a scheme of forming a Cu(In,Ga)Se2 (CIGS) based-light absorbing layer by simultaneously or separately evaporating Cu, In, Ga, and Se and a scheme of performing a selenization process after a metallic precursor film has been formed. The energy band gap of the light absorbing layer is in the range of about 1 eV to about 1.8 eV.
Thereafter, a buffer layer including cadmium sulfide CdS is formed on the light absorbing layer through the sputtering process. The energy band gap of the buffer layer is in the range of about 2.2 eV to about 2.4 eV. Thereafter, a high-resistance buffer layer including ZnO is formed on the buffer layer through the sputtering process. The energy band gap of the high-resistance buffer layer is in the range of about 3.1 eV to about 3.3 eV.
Thereafter, groove patterns may be formed in the light absorbing layer, the buffer layer, and the high-resistance buffer layer.
Thereafter, a transparent conductive material is stacked on the high-resistance buffer layer, and the groove pattern is filled with the transparent conductive material. Accordingly, after forming a transparent electrode layer on the high-resistance buffer layer, connection wires are formed in the groove pattern. The material constituting the transparent electrode layer and the connection wires may include aluminum-doped zinc oxide. The energy band gap of the transparent electrode layer is in the range of about 3.1 eV to about 3.3 eV.
Thereafter, the groove patterns are formed in the transparent electrode layer, so that a plurality of solar cells can be formed. The transparent electrodes and the high-resistance buffers correspond to the cells. The transparent electrodes and the high-resistance buffers may be arranged in the form of a stripe or the form of a matrix.
The transparent electrodes and the back electrodes are misaligned with each other, and electrically connected to each other by the connection wires. Therefore, the solar cells can be electrically connected to each other in series.